Instrument for drawing curves.



No; 772,622. PATENTED OCT. 18, 1904.

I E. J. LORING. v

INSTRUMENT FOR DRAWING CURVES.

APPLICATION FILED FEBJZ. 1904.

-N0 MODEL.

" WITNESSES UNITED STATES Patented October 18, 1904.

P TENT OFFICE.

ERNEST J. LORING, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR OF LORING, or

INSTRUMENT FOR DRAWING CURVES.

SPECIFICATION forming part of Letters Patent No. 772,622, dated October18, 1904.

' Application filed February 8, 19(14. Serial No. 192,515. (No model.)

To all whom, it may concern;

Be it known that I, ERNns'r J. LORING, of Somervill'e, in the county ofMiddlesex and State of Massachusetts, have invented certain new anduseful Improvements in Instruments for Drawing Curves, of which thefollowing is a specification.

This invention has for itsobject to provide an instrument adapted for adrafting instru ment to generate or test tangential curves, &c., oradapted for-use as a testing or working templet for any constructionalor mechanical work requiring the generation or transference ofrelatively flat curves.

To this end it embodies a resilient ruling guide or edge of adjustablecurvature which hasa characteristic or predetermined law of curvatureand is mounted and adjusted in a novel manner, as will be fullyexplained.

Of the accompanying drawings, Figure 1 represents a plan view of adrafting-board and T-square and an instrument embodying my invention.Fig. '2 represents a perspective view of the instrument, showing the topplate separated from the rest of the instrument. Fig. 3 represents anenlarged plan view of one end of the instrument. Figs. 1 and 5 representdetail perspective views illustrating twomodified forms of mechanism foradjusting the rulingguide.

The same reference characters indicate the same parts in all thefigures.

The instrument comprises a frame composed of parallel flat side plates10 10, separated by a thin back strip 11 and shallow posts 12 12 andconnected by screws 13,whose heads are flush with or below theplate-surface. .The back edge 1 1 of the instrument is a straight edge,and the front edge is a rulingguide 15, of adjustable curvature, fixedin its intermediate portion at16 at a point-about one-third of thedistance from one end of the instrument and having free end portions orextremities, one of which is thus made about twice the length of theother. These extremities are engaged by pivoted levers 17 in the form ofthe invention shown in Figs. 1,2,

hereinafter more 7 and 3, having projections 18 occupying curvedcam-slots 19 in the frame-plates, the

.pivots of the levers being eccentric to the 2, and the ends of theprojections 18 indexmarked, whereby different predetermined adjustmentsmay be effected.

The ruling-guide 15 is flexible and resilient between its fixed portion16 'and its two free extremities, so that according to the degree ofpressure exerted by the levers 17 in their different positions theextremities or end portio'ns of said ruling-guide will assume differ--ent degrees of curvature. The curvature of each end varies according toa characteristic or predetermined law-that is to say, the ruling-guideis so regulated in dimensions and material between its fixed point andfree extremities as to invariably assume the same curvature for anygiven position of either extremity. The rate of curvature of the par-'ticular curve for which the instrument may be arranged can be expressedas a continuous or progressive function of the length of arc,andtheinstrumentwill generate such a curve with closest accuracy. .Itmay also be used to transfer any curve from workto drawa ing if saidcurve is of the samecha'racteristic of curvature as that for which theparticular instrument is fitted. I

It is obvious that by properly constructing the instrument its workingedge will bend to a curve which may be of uniform curvature or one whosecurvature either increases or decreases from the tangential point, thisincrease or decrease progressing at any predetermmed rate.

The manner of using the instrument is illustrated in Fig. 1, in which 2Ois a draftingboard, and 21 a T-square. of the instrument is placedagainst the edge of the T-square, as shown, and the opposite ruling edgeemployed to plot the desired curves on the drawing-surface, the rulingedge, as will be evident, being continuous and forming the outermostedge of the. instrument, so that continuous curves may be drawn.

Preferably the ends 22 of the frame are at right angles with the backedge 14 and the projecting handle portions of levers 1'7 arrangedentirely within the rectangular limits of said back and end edges, sothat the instrument may be used in any position in cooperation withT-squares, triangles, straight-edges, &c. By making one of the twoindependently-adjustable portions of the ruling-guide longer than theother the ends are differentiated and the instrument adapted to a largevariety of curved forms. Opposite the fixed point 16 the ruling edge ofthe guide 15 is always parallel to the straight rear edge 14 andperpendicular to the end edges 22. Hence the instrument is readilyplaced to its work. It is one of the features of the instrument thatthere are no projections beyond the planes of the parallel fiat surfacesof the frame, thus making the instrument perfectly reversible.

It will be seen, particularly in Fig. 3, that the front edge of theframe at the shorter end recedes from the straight line of the rest ofthe edge, as shown at 23, beginning in the vicinity of the fixed point16. The shorter end portion of the ruling-guide 15 is adapted to takeeither a convex line, as shown in full lines in said figure, or aconcave line, as shown in dotted lines, or astraight line between thetwo. It is obvious that this might also apply to the longer portion ofthe ruling edge, although not so shown.

The construction of the instrument renders it compact, and the locationof the centers of gravity of the several parts all in the same planeconduces to strength and tends to prevent twisting of the instrument.

Various types of operating mechanism may be employed. Fig. at shows amodification in which a pivoted cam plate or lever 24 engages theruling-guide 15. In Fig. 5 an eccentric 25, journaled in theframe-plates 10, has a strap 26, whose head rocks in a socket in theruling-guide, whereby motion is imparted in both directions, as in Figs.1, E2, and 3.

Various other modifications may be made without departing from thespirit of the invention.

The instrumentmay be made in various The back edge 1 L for drawing theentasis of a column a similar instrument of greater size may be used asa templet in the production of the column itself.

I elaim 1. A drafting instrument comprising a frame having a straightback edge, a rulingguide of variable curvature having a point fixed withrespect to the said back edge and tangent to a line parallel with theback edge, said guide having a free working edge continuous across saidpoint of tangency and a shiftable extremity, and means for shifting saidextremity in a direction transverse to said back edge.

2. A drafting instrument con'iprising a frame having a straight backedge, a rulingguide of variable curvature having a point fixed withrespect to the said back edge and tangent to a line parallel with thelatter, said guide having a free working edge continuous across saidpoint of tangency and shiftable extremities on both sides of said point,and means for shifting said extremities in a direction transverse tosaid back edge.

3. A drafting instrument comprising a frame having a straight back edge,a resilient ruling-guide having a fixed point of attachment to saidframe and a shiftable extremity, said guide being free between saidfixed point and extremity and so constructed as to assume predeterminedcurvatures varying according to the degree of pressure exerted on saidextremity, and means interposed between the frame and said extremity forshifting said extremity transversely of said back edge to impart varyingflexure to the guide.

1. A drafting instrument comprisim a frame, a resilient ruling-guidehaving a fixed point of attachment thereto and a shiftable extremity,and a pivotally-movable adjusti nglever interposed between said frameand extremity and so arranged as to act with mechanical advantage onsaid extremity.

5. A drafting instrument comprising a ruling-guide having a continuousruling edge provided with independently-shiftable end portionspossessing characteristic laws of ourvature, means for holding saidruling edge immovable at a point intermediate of its ends, and means toindependently adjust the end portions of said ruling edge to differentdegrees.

6. A drafting instrument comprising a frame, a ruling-guide having apoint fixed on said frame and a shiftable extremity and possessing acharacteristic law of curvature, and means acting on said extremity toadjust said guide to convex and concave curves or a straight line.

7. A drafting instrument comprising a frame, a ruling-guide having afixed point of attachment thereto and shiftable end portions ofdifferent lengths and characteristic laws of curvature on opposite sidesof said fixed point, and means interposed between said frame and edge,and means for independently adjusting.

the curvature of the end portions of said guide.

10. A drafting instrument comprising a frame composed of side platesseparated by a space, a ruling-guide of adjustable curvature fillingsaid space and having one edge protruding beyond said plates, and meansfor varying the curvature of said guide.

11. A drafting instrument comprising'parallel fiat frame-plates, anadjustable rulingguide mounted between said plates, and means mountedbetween the plates to adjust the curvature of said guide, the planes ofthe two sides of the instrument being formed by the outer surfaces ofthe plates and being free from outward projections. v

12. A drafting instrument comprising a frame having straight back andend edges in rectangular relation, a ruling-guide of adjustablecurvature carried by said frame, and adjusting means for saidguidearranged entirely within the rectangular limitsof said back and endedges. Y

. I. In testimony whereof I have aflixed my signature in presence ,oftwo witnesses.

ERNEST J. LQRING. Witnesses:

R. M. PIERSON, A. C. RATIGAN.

